SOLUTION: John is twice as old as his son. In 42 years, the ration of their ages will be 4:3. what is the sons current age

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Question 223883: John is twice as old as his son. In 42 years, the ration of their ages will be 4:3. what is the sons current age
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
: John is twice as old as his son.
J = 2S
:
In 42 years, the ratio of their ages will be 4:3.
:
%28J%2B42%29%2F%28S%2B42%29 = 4%2F3
:
what is the sons current age
:
Replace J with 2S in the above equation
%282S%2B42%29%2F%28S%2B42%29 = 4%2F3
Cross mutiply, find S
3(2S + 42) = 4(S + 42)
:
6s + 126 = 4S + 168
:
6S - 4S = 168 - 126
:
2S = 42
s = 42%2F2
s = 21 is Son's age:
:
:
See if that is true
%2842%2B42%29%2F%2821%2B42%29 = 84%2F%2863%29 = 4%2F3